Vacuum pump



Cil

Y a body of oil for the Patented Nov. 8, 1927.

UNrrED STATES hasta;

PATENT OFFICE.

OSKAR SEITZ, OF BADEN, SWITZERLAND, ASSIGNOR TO THE FIRM GLEICHRICHTER- AKTIENGESELLSCHAFT, 0F GLARUS, SWITZERLAND.

VACUUM rUMr.

Application `filed. June 27, 1921, Serial No.

This invention relates to vacuum pumps of the mechanical type in Which a body of oil is employed as a sealing medium for thev compression chamber and as a source of supply for Working parts in the compression chamber.` A

, The general object of the invention is the rovision of a construction which Will contribute to the eiiiciency of the pump.

A more specific object is the provision of a pump construction of the sort indicated in which provision is made for the separation of Water and other foreign substances from the` Working oil incident to 7 the operation of the pump.

Another object is the provision of a constructiony which will contribute to the separation from the oil of gases discharged by the pump and prevent discharge of the oil or its loss from the chamber ywherein it is employed as a medium for preventing back flow of gasl into the pump chamber.

Other and further objects Will be pointed out or indicated hereinafter, or will appear to one skilled in the art upon an understanding of the invention or its cmploy ment in practice.

In the accompanying drawing forming a part of this specification, I illustrate, in diagrammatic fashion, one arrangement of apparatus constituting` .an embodiment lof the invention, but it islto be understood that thisis presented for purpose of illustration only and is not to be construed in any fashion for the purpose of limiting the claims short of the true and most comprehensive scope of the invention in the art. Y

In the drawing, the figure is a diagrammatic illustration of a vacuum pump in sectional eleve tion.

. The invention has to do with vacuum pumps, such as of the rotary or gear types, in which a body or bodies ofvoil are einployed for providing Working parts in. the pump chamber with a suitable scaling lubricant and forproviding a seal at the outlet of the pump chamber for preventing back In some designs flow of gases thereinto.

of pumps Iof this type, it has been customary to surround the pump chamber itself with purpose of sealing f the Working chamber against ingress of atmosphere or surrounding gases,y For purpose .of convenient differentiation, the pardensed, by compression in the pump chamand also for other impurities 480,808, and in Switzerland July 17, 1920. i

ticular portion of the oil body employed for the last mentioned use maybe designated the sealing oil, While-the portion of the oil body which is remployed for furnishing lubricant to the Working parts inthe compression chamber and for sealing the outlet co of the compression chamber against back flow, may be designated the Working oil.

In operation of pumps of this description, particularly in evacuating apparatus containing vapors, or in installationsin which such pump is employed as a preliminary pump ahead of another vacuum pump of the vapor jetor diffusion type, it has'been observed that the volumetric efficiency is adversely affected by the presence of'vvater or other foreign liquid in the Working oil.

The air coming from the suction'pipe contains a greater or less quantity of Water vapour in solution. This vapour is. conberL to fine drops of iva-ter Which mingle with ythe Working oil and may be again evaporated in thelow pressure side of the pump if reintroduced into the pump chamA ber with the Working oil. This has the resultthat the vacuum is reduced by the vapourpressure of fthe Water acting as a partial pressure of the mixture of oil and water in the pump. Further, foreign 'bodies of any kind, if introduced into thervorking chamber With the oil, may also interfere With the internal moving rparts in such a dcgree` as to diminish the vacuum andthe volumetric output. f

Experience has shown-that this drawback can r generally be counteracted only by a thorough cleaning of the pump and renewal of the oil.

In the improved construction of. rotary pumps according to this invention the arn rangement is such that the dome, contain-- ing the Working oil, is in direct communica.- tion With the oil chamber of the pump casing which is situated below the rsaid dome and contains'the sealing oil, in such a manner that the space in the pump casing vserves as ay separating chamber for the Water that passes from the pump into the Working oil, which may settle out of the oil in the dome; such Water and impurities being permitted to collect on the bottom of the casing whence they can be discharged through a discharge orifice withf l int-alte passage c and forces :it through the.

discharge passage (Z and the non-return valve e into the exhaust dome f. ln its course, the mixture that has been carried over is condensed by thecompression of the air and mingles in the form of line drops of Water With the Working oil thatl lubricates the pump, and is driven out, together with the air, through the non-return valve c into the Working oil in the dome f, which surrounds the outlet valve and supplies the Working parts of Vthe pump, by way of the passage d, with the necessary lubricant.

The air expelled through the discharge passage d passes through the bodyV ot sealing oil Z and escapes at the top o't the dome through the chimney p. The WaterV and the other impurities discharge intothe body oi sealing oil Z settle to the bottom oi" the dome and pass through the aperture h into the chamber m of the sealing oil and finally collect on the bottom ol` the casing at n.

Herein the sealing oil chamber the separated foreign matter can remain safely Without influencing the Working of the pump, as the sealing oilv is not subject to agitation, and can be discharged at any time on removal o't the blow-olf scrciv 0.

Further, a separating vessel g may be provided/in the exhaust dome f, said vessel being so constructed that the air can escape, Whilst, in the case of an increased delivery oi air such as occurs during the starting'vvith atmospheric aii-or by reason of leakage, .oil is prevented 'trom being ejected into the atmosphere by the exhaust.

ln such an operation, especially in pumps ivith'a large output, or a higli speed of revolution, a mixture of oiland air boils very stroi'igly in the exhaust dome By .the insertion ot the separating vessel g having downwardly directed openings 1I and 7c, the oil remains behind in the saidvesscl, Whereas the air able to escape through the chimney p into the atmosphere.

As the vacuum increases, the boiling diminishes in violence owing to the decreasing delivery of air in relation to the atmospheric pressure, and then the oil that is colf lect-cd in' the separating vessel flows gradually back through the d 'ainage apertures 70,. in the chamber Z,

Leasess oil chamber tor confining a body ofoil about' the pump cylinder, an exhaust chamber for continingi a body oit oil about the outlet of the discharge passage, said exhaust cham'- bei'rbeing located above the. sealing oilcham-v er and being in open communication.thereivith at a level beloiv the outlet end of the discharge passage.

2. ln a vacuum piimp,.in combination, a pump casing affording. an exhaust lchamber and ay sealing oil chamber, a: pump cylinder located Within the sealing oil chamber 'and having a discharge passage With'its outlet f' in the exhaust chamber, saidfchambers arranged to coniie a body of oil aboutgthe pump cylinder andits outlet,l pump mechanism operable in the pump cylinder to discharge fluid into the body oit oil in the exhaust chamber, iid exhaust chamber having` communication at its bottom Withthe sealing oil chamber at a leveljbelovv the out'-v let end of the discharge passage, and the seal-ing oil chamber being provided With a clean-out passage in its lower portion.

3. In a vacuum pump, in combinatioma pump cylinder having a discharge passage, pump mechanism operable in said` pump cylinder to discharge gases through said passage, an exhaust chamber into Which said discharge passage opens, said exhaust chamber arranged to hold a bodyof oil covering the outlet of the discharge passage, and a `casing alltel-ding a sealing oil chamberfor confining a body oli/oil about the pumpscylinder, said sealing oil chamber and exhaust chamber` having communication vthrough an opening beloiv the outlet end; of the discharge passage, said openii'igfarranged to permit settling ol material from the body oit' oil in the exhaust chamber into the sealing oil chamber. V

fl. ln a vacuum pump, in combination, an

exhaust chamber, a sealing oil chambenfa pump cylinder in thi-scaling oil' chamber and having a passage comu-iunicatiiig With 4the exniust chamber, said exhaust chamber arranged to hold a body of oil covering said communicating passage, the sealing oil` chamico berarranged to hold a body of oil about the L pump cylinder, said sealing oil chamber and exhaust chamber communicating by Way ot an opening arranged beloiv that of the communicating passage 1n the exhaust chamber,

said opening arranged to permit settling of Y material Jfrom oil in the exhaust chamber into the sealing oil chamber.

5. In a vacuum pump, in combination, an exhaust chamber arranged to hold a body of oil, a pump cylinder having a` communicating passage opening in the exhaust chamber above the bottom thereof, pump mechanism operable in said pump cylinder, a sealing oil chamber about the pump cylinder, said sealing oil chamber and exhaustchamber being in open communication at the bottom of: the latter, and a clean-out passage communicating with the bottom of the oil chamber.`

6. In a vacuum pump, in combination, a pump cylinder having a discharge passage,

pump mechanism operable in said pump cyliiider to discharge gases through said passage, an exhaust chamber into Which said discharge passage has an outlet, said exhaust chamber arranged to hold a body of oil covering the outlet of the discharge passage, a separating vessel disposed in the upper portion of the exhaust chamber and having communication exteriorly thereof, said vessel being provided with restricted apertures at its upper portion having communication with the interior of said exhaust chamber and an aperture at its lower portion for draining into the exhaust chamber.

' In testimony whereof I have signed my name to this specification.

OSKAR SEITZ. 

